Fix compile-time error in color selector control
Ignore README.txt backup in primary directory
Fix an interface synchronization bug
Do not render the "unsaved changes" image until after the form is visible

This allows the color management code to correctly identify the
rendering monitor, so it can assign the proper profile
Move some color management code to pdLayer class

Just a few commits earlier, I said I wasn't going to do this - but it
has huge benefits, so I changed my mind!

Instead of baking color management into the preview user control, I have
moved the color management code into the pdLayer RenderToPictureBox
function.  This function is used throughout the program - for tool
previews, the unsaved changes dialog preview, batch convert image
previews, etc.  By placing a color management call there, it guarantees
that whenever a layer (or eventually, a composited image) is rendered to
screen, that proper color management will be applied based on the
destination picture box's location.

Not only does this save me a bunch of duplicate code, but it also
future-proofs color management for future layer renders (like thumbnails
on a layers dialog).
Activate color management for the image tabstrip